1. Technical Field
The present invention relates to a method for forming a film pattern, and a method for manufacturing a device, an electro-optical device, an electronic apparatus, and an active matrix substrate.
2. Related Art
As a method for forming a wiring line, which has a predetermined pattern, and is used in electric circuits and integrated circuits, photolithography has been widely used. However, the photolithography needs large-scale equipment such as vacuum apparatuses and exposure apparatuses, and sophisticated processes to form the wiring line having a predetermined pattern. In addition, almost all of materials are wasted due to a low efficiency of about several percent in using the materials, resulting in high manufacturing costs.
Alternatively, a method is proposed in which a wiring line having a predetermined pattern is formed on a substrate using a droplet discharge method (called an inkjet method) in which a liquid material is discharged from a liquid discharge head as a droplet. For example, the method is disclosed in JP-A-11-274671 and JP-A-2000-216330. In the inkjet method, a liquid material (functional liquid) for a pattern is directly patterned on a substrate, and then the patterned material is subjected to heating or is irradiated by laser so as to form a desired pattern. Accordingly, the method has an advantage in that no photolithography is required, processes can be drastically simplified, and the amount of consumed raw material can be reduced since the row material can be directly applied on a patterning position.
Recently, circuits included in devices have been highly densified. This requests, for example, wiring lines to be further reduced in width. However, in the pattern forming method using the droplet discharge method described above, it is difficult to stably form a fine pattern since a discharged droplet spreads on a substrate after landing on the substrate. Particularly, when the pattern functions as a conductive film, spreading of the droplet causes a liquid pool (bulge), which may cause a failure such as wire breakage or short. As an alternative, a technique is proposed in JP-A-2005-12181. The technique employs a bank structure including a region for forming a wide width wiring line, and a region for forming a fine wiring line that is formed so as to be connected to the region for forming a wide width wiring line. In the technique, a functional liquid is discharged to the region for forming a wide width wiring line, so that the functional liquid flows into the region for forming a fine wiring line by a capillary phenomenon, thereby a fine wiring pattern is formed.
Here, if the difference is significant between the widths of the region for forming a fine wiring line and the region for forming a wide width wiring line, to which the functional liquid is discharged, the amount of functional liquid that flows into the region for forming a fine wiring line by a capillary phenomenon runs short. This is because that the functional liquid usually flows along a bank that defines the region for forming a wide width wiring line. As a result, a problem arises in that the film thickness of a formed fine wiring pattern is thinner than other wiring patterns.
As an alternative to increase the thickness of a fine wiring pattern, for example, a method can be employed in which a part of the width of the region for forming a wide width wiring line is narrowed so as to increase a flowing amount of a functional liquid into a region for forming a fine wiring line from the region for forming a wide width wiring line.
However, it is difficult to adequately control the flowing amount of the functional liquid in the above-described case where the amount of the functional liquid flowing into the region for forming a fine wiring line (a first pattern forming region) is increased by narrowing a part of the region for forming a wide width wiring line (pattern forming region). For example, if the function liquid flows into the region for forming a fine wiring line too much, the thickness of the fine pattern becomes thicker than those of others, resulting in a difference in thickness between the fine pattern and others.
As a result, if the technique is, for example, applied to form a gate wiring line and a gate electrode continued from the gate wiring line, stable transistor characteristics are hardly achieved due to the difference in thickness between the gate wiring line and the gate electrode.